如何在c中设置UDP套接字中的源端口？

Posted 2023-04-15

【中文标题】如何在c中设置UDP套接字中的源端口？

【英文标题】：How to set the source port in the UDP socket in c?

【发布时间】：2012-04-10 00:16:59

【问题描述】：

谁能告诉我如何在 UDP 套接字中设置源端口地址？我的客户端应用程序需要将数据包从 57002 端口发送到服务器端口 58007 。

【参考方案1】：

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define DST_PORT    58007
#define SRC_PORT    57002

#define IP      "127.0.0.1"

int main(int argc, char *argv[]) 
    struct sockaddr_in addr, srcaddr;
    int fd;
    char message[] = "Hello, World!";

    if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) 
        perror("socket");
        exit(1);
    

    memset(&addr, 0, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = inet_addr(IP);
    addr.sin_port = htons(DST_PORT);

    memset(&srcaddr, 0, sizeof(srcaddr));
    srcaddr.sin_family = AF_INET;
    srcaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    srcaddr.sin_port = htons(SRC_PORT);

    if (bind(fd, (struct sockaddr *) &srcaddr, sizeof(srcaddr)) < 0) 
        perror("bind");
        exit(1);
    

    while (1) 
        if (sendto(fd, message, sizeof(message), 0, (struct sockaddr *) &addr,
                sizeof(addr)) < 0) 
            perror("sendto");
            exit(1);
        
        sleep(1);
    
    return 0;

【讨论】：

如果源端口未绑定，如何选择随机源端口以及范围可以以某种方式控制/指定？

【参考方案2】：

bind(2)它。使用INADDR_ANY 地址和您的端口号。

【讨论】：

链接的手册页有一个示例。这是另一个alas.matf.bg.ac.rs/manuals/lspe/snode=47.html

【参考方案3】：

struct sockaddr_in servaddr,cliaddr;
sockfd=socket(AF_INET,SOCK_DGRAM,0);

servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr=inet_addr(argv[1]);
servaddr.sin_port=htons(32000); //destination port for incoming packets


cliaddr.sin_family = AF_INET;
cliaddr.sin_addr.s_addr= htonl(INADDR_ANY);
cliaddr.sin_port=htons(33000); //source port for outgoing packets
bind(sockfd,(struct sockaddr *)&cliaddr,sizeof(cliaddr));



use sendto with servaddr 
use recvfrom with cliaddr
if u check wireshark u will see source port as 33000 and destination port as 32000 for sendto operation

【参考方案4】：

 struct sockaddr_in sa;
 int ret, fd;

 memset(&sa, 0, sizeof(struct sockaddr_in));
 sa.sin_family = AF_INET;
 sa.sin_port = htons(LOCAL_PORT);
 sa.sin_addr.s_addr = inet_addr(LOCAL_IP_ADDRESS);


 ret = bind(fd, (struct sockaddr *)&sa, sizeof(struct sockaddr));